chu software can be used in combination with
NTP to produce a stratum-1
time server.This is done using the LOCAL reference clock module in ntpd. For example, if you are using ntpd version 4, the following configuration works nicely:
server 127.127.1.0 prefer fudge 127.127.1.0 stratum 0 refid CHU disable ntp
chu communicates with ntpd via the kernel's adjtimex()
API. Note that adjtimex() is the Linux API, and may be called
ntp_adjtime() on other systems.
The system clock is disciplined by chu, not by ntpd.
chu appropriatly maintains the status flags and error estimates
so that ntpd can do the right thing.